Fig. 3. Assessments of muscle protein fractional synthetic rate (FSR) using heavy water labeling method. (A) A small dose of heavy water (deuterium oxide, D2O) is orally administered to achieve target enrichment (~1% for humans and ~5% for animals) and assess FSR of muscle protein. (B) D2O administered into the skeletal muscle will form mono-deuterated water (i.e., 2H1HO). The 2H will be incorporated into precursors, such as amino acids (AAs). The 2H-labeled AAs are incorporated into new muscle proteins. (C, D) Muscle protein FSR (individual, subgroup, or mixed proteins) is determined based on the information on precursor AA enrichment and changes in product enrichment over a defined time. (E) In addition, enrichment is accessed using gas or liquid chromatography-mass spectrometry in samples obtained via needle biopsy, blood, or urine. This figure was created with BioRender.com.
mCK = muscle creatine kinase.
© 2022 Ann Clin Nutr Metab
